A. Field of the Invention:
This invention relates generally to computerized controllers of machine processes in a host machine such as an electrostatographic copier and particularly to controllers having capabilities for non-volatile memory when controller power is down for retaining memory and also for processing the current I/O to memory operation.
B. Prior Art:
In the past, controllers having a computer would have memories that would be susceptible to a power-down condition in that the content of RAM memory would be erased once power went below a predetermined threshold. This would be particularly onerous where the controller is sequentially directing the host machine in so much as a complete restart from the beginning of the sequence would be required. Even in those system where a conventional non-volatile memory might be had, there still remained the problem of losing the current I/O to memory operation even when the memory itself is retained in a power-down condition. Accordingly, a complete restart to beginning of sequence would also be required here. A final problem involves the power requirements of the circuitry servicing the non-volatile memory. It is particularly important to have a low-power drain during a power-down condition thus enabling the battery servicing the non-volatile memory to last beyond the down period thus retaining the RAM memory.